Why Won’t My Self-Priming Pump Suck up the Water?

Posted On Posted on 1st November, 2022 by Ozz

A common question we get asked is why my self-priming pump is not working. The fact is that there could be any number of reasons as to why your system isn’t functioning correctly. In order to help our customers determine the cause of the fault, we’ve highlighted some of the most common problem points. Check out the full blog below, and if it doesn’t answer your question, our customer care team will be happy to help!

Obviously, there are many factors that could be causing the pump not to be working, so below we have set out a few of the most common ones:


Tip #1: Check if Your Pump is Primed

If your pump is running but not lifting the water out of the pit and discharging, the first thing to check is whether the pump has been primed.

A common misconception is that a self-priming pump can just be started up and it will start to work. However, that isn’t actually the case. A self-priming pump needs to have liquid to fill the priming chamber, which then allows the pump to draw the liquid out of the priming chamber. Once a pump is primed initially, this point will then hold the water for future use thereafter.


Tip #2: Check if Your Suction Line is Blocked

If our first tip doesn’t address your pump issues, the second thing to check is if the valves are all correctly opened, and the suction line is not blocked.

If the line is blocked, this may need to be jetted or the tank cleaned out. Also, check any filters on the system for blockages.


Tip #3: Check if Your Non-return Valve Has Failed


Another key problem point for self-priming pumps is faulty nonreturn valves.

These can be held open with waste debris and will fail due to age, stopping the pump from functioning correctly. Before you make any decisions, check to see if this is the case with your pump system.


Tip #4: Ensure Your Power Supply is Working Correctly 

If your pump is not running at all – as with any pump – the first thing to check is the power supply to the pump along with the controls, to ensure these are working correctly.

If there is power going to the pump, the pump is likely to have a failed motor. Alternatively, it could be seized up which then calls for pump engineers to rectify your issue.


Tip #5: Ensure Your System is Regularly Re-Primed

Another common issue in self-priming pumps is that they can continually lose prime. This means that they have to be regularly reprimed. Here are a few factors that can cause this:

  • A leaking mechanical seal
  • Nonreturn valve letting by; and
  • Failed casing gaskets


Tip #6: Double Check Your Pump Specifications

Finally, if it is a new installation and the pump is not lifting the water out of the pit, and the pump is primed, the specification of the pump and the size of suction pipe work should be checked.


Got a Problem with Your Self-Priming Pump? Call on the Pump Pros!

If you require more information on self-priming pumps, their applications or have a fault with one – please reach out to one of our team on 01604 648 800. Alternatively, contact us right here!

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